We plan to continue our efforts to distinguish different species of motoneurons within the plantaris pool. We shall use the technique developed in this laboratory to measure the critical firing level (CFL) of motoneurons. In particular, the effects of inhibitory inputs are being examined to determine how they are distributed in the pool and whether they affect different species of motoneurons in different ways. Pairs of motoneurons of similar CFLs are being examined to determine whether the ratios of their firing rates are similar during pure excitation and excitation plus inhibition. The objective of these experiments is to determine whether inhibition is quantitatively similar to a reduction in excitation in its effects on firing rates.